Synthesis of 1,2-diaminotruxinic d-cyclobutanes by BF₃-controlled [2 + 2]-photocycloaddition of 5(4<i>H</i>)-oxazolones and stereoselective expansion of d-cyclobutanes to give highly substituted pyrrolidine-2,5-dicarboxylates

Sierra, Sonia ; López, Rosa ; Gómez-Bengoa, Enrique ; Falvello, Larry R. (Universidad de Zaragoza) ; Urriolabeitia, Esteban P.

Resumen: The irradiation of (Z)-4-arylidene-5(4H)-oxazolones 1a–1u with blue light (465 nm) in the presence of the photosensitizer [Ru(bpy)3](BF4)2 (2.5 mol%) and the Lewis acid BF3·OEt2 (2 equiv.) in deoxygenated methanol at room temperature affords the corresponding 1,2-diaminotruxinic cyclobutane bis-amino esters 2a–2u stereoselectively as the δ-isomer. Characterization of cyclobutanes 2 shows that the photocycloaddition takes place by the coupling of two Z-oxazolones in a head-to-head 1,2-anti way. This change in the orientation of the coupling is promoted by O- or/and N-bonding of the BF3 additive. The δ-cyclobutanes 2 undergo a ring expansion when heated in methanol in the presence of NaOMe (1/1 molar ratio) to give densely substituted pyrrolidine-2,5-dicarboxylates 3 in a regio- and stereoselective way. The mechanism of the cyclobutane-to-pyrrolidine ring expansion has been elucidated using DFT methods.

Idioma: Inglés

DOI: 10.1039/d3ob00284e

Año: 2023

Publicado en: Organic & Biomolecular Chemistry 21, 15 (2023), 3203-3213
ISSN: 1477-0520

Factor impacto JCR: 2.9 (2023)

Categ. JCR: CHEMISTRY, ORGANIC rank: 13 / 58 = 0.224 (2023) - Q1 - T1

Factor impacto CITESCORE: 5.5 - Physical and Theoretical Chemistry (Q2) - Organic Chemistry (Q2) - Biochemistry (Q3)

Factor impacto SCIMAGO: 0.607 - Organic Chemistry (Q2) - Physical and Theoretical Chemistry (Q2) - Biochemistry (Q3)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E11-20R
Financiación: info:eu-repo/grantAgreement/ES/DGA/E19-20R
Financiación: info:eu-repo/grantAgreement/ES/MCINN-FEDER/PGC2018-093451-B-I00
Financiación: info:eu-repo/grantAgreement/ES/MICINN AEI PID2019-110008GB-I00
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2019-106394GB-I00

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)